Some of these tips I read from a beginners guide some time ago.
1. If you ever have to run toward an archer without a shield, you can accomplish this without dying by dodging the arrows. Run straight at the archer and when you hear that the archer is about to release his arrow, turn and run at an angle until the danger passes, then resume your course.

2. When fighting cavalry, try to position yourself with your back against a wall.

3. If you are facing a combination of archers and infantry, hide behind a house or something so that archers won't be able to fire at you while you deal with the infantry.

4. This cannot be stressed enough: do not fight in wide open spaces. Don't get surrounded.

5. Don't chase enemies if they retreat into their allies. One extra kill isn't worth waiting 5 minutes for respawn. Don't get surrounded.

6. Be aware of your surroundings. Glance occasionally at your flanks so that you... don't get surrounded. Player IndiaQuinn suggests that you keep an eye out for allies who are under attack.

Quote:If your friend decided to leave the line and charge the enemy pack alone  there is not much you can do or should do. Trying to save the fool will likely lead to getting killed yourself. But always keep an eye open where there  the pressure is. If a friend is about to go down or a part of the line is wavering. Or as Blondin said, if you keep an overview you easily see when archers are in the danger zone. Help out.  When close to your archer friends, avoid sudden crossings of his/their line of fire.

If enemies are busy killing your friend, they leave a lot of opportunities on their flanks. Fast swings can easily decimate the attackers. Stay close to your ally if you do this, or the enemy group will split and overwhelm you all. [Editors Note: It is a good idea to have a long weapon so that you can attack from the flank with less of a risk of attracting enemy aggro]

When fighting the enemy in pairs, try not to swing your weapon at the same time. Two successive swings will like give a great hit chance on the enemy. This works very well against Huscarls and Zweihanders.

7. Roran's Target Priority Hierarchy:
Cavalry:
cavalry-archers-infantry-pikemen
Infantry:
Pikemen-infantry-archers-cavalry( or cavalry first if there is too much cav for the cav to handle)
Archers:
cavalry-archers-pikemen-infantry (since those carry shields)

8.If you manage to kill a mounted soldiers horse, attempt to immediately kill the rider. Do not go dismounting more soldiers. This is so that you can face the dismounted troop with less distraction while the other riders are attempting to turn around and hit you again. Always finish the rider off when you kill off his horse (unless it's too dangerous, in which case, get to better ground).

9. Try to avoid crossing an archer's line of fire as it will cause them to damage themselves. It also means one more enemy isn't dead/weakened.

Much of this set-up is informed by observations of other effective players. The topic of equipment is always up to debate, but my preferred set-up involves:
1. a long range weapon (e.g. glaive, hafted blade) - primary tool of murder; slaughter them before they get close. Also, swinging side to side is generally more effective, as you have a greater chance of hitting the enemy. I also suggest using the autoblock that god has so graciously granted us, even if it goes against your principles.

2. a quick weapon that can be used with a shield (e.g. elite scimitar) - good for retreating while fighting shield infantry, or, if ever needed, charging archers). If you find yourself alone and are forced to retreat from a horde of enemies, I consider it a good time to whip out your shield and scimitar. If you can back away and get the enemies in a line, you have a higher chance of killing at least a few of them.

3. Deployable shields - most definitely a good idea. These require quite a bit of teamwork to properly employ though, so you need to have people who will agree to equip them and use them with you. These shields stop cavalry in their tracks, allowing you to slaughter them where they sit. Not only is it useful against cavalry, infantry also succumb to the power of deployable shield walls. No longer will you have to fear attacks from the flank! Well... kind of... maintain some of that fear and keep an eye out for those strange ones who are smart enough to run around the shield wall. Shield walls should be deployed with enough space between them to execute a downward slash, but little room to go between. Intentionally leaving a hole in the wall large enough for one enemy to go through is a good idea as well. This will funnel the enemies, giving you the same kind of advantage attacking in a concave will (the ability to attack one man from multiple angles). When using this item, I switch out the pike, as you no longer will have trouble with charging horses.

4. When you reach Sergeant class, you unlock an extremely powerful weapon: the morning star. The Morningstar has 38 pierce damage, overhead crushthrough, 95 speed, and 85 reach. You may use it with one or two hands. This weapons is very good against skirmishers and other shielded or armored foes and I highly recommend using it when you reach sergeant.

5. According to Simpli, the Pike is a versatile weapon for lower level players. It allows one to safely attack enemies while your allies act as a buffer between you and the enemy. It is a good choice for those who cannot yet afford expensive armor.

Be a team player. I realize it is difficult being part of a minority of players who try to play cooperatively, but persist, and others will eventually become willing to try to play in this way. Communicate with your allies and you can win a hundred battles without jeopardy! (DISCLAIMER: This statement is purely hyperbolic) But seriously, if you were in a situation where you were liable to get killed at any moment, would you be rushing in to find 1 gold from a fallen enemy? Would you be withholding the means to purchase godly armor in the face of a Nord invasion? Think about it, guys... Think about it... (This statement ended up being less serious than intended). Don't get surrounded!

I hope this guide has been informative and I hope that more players in the community become more willing to play as a team, and not for gold.